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CVE Record

CVE-2021-47250: net: ipv4: fix memory leak in netlbl_cipsov4_add_std

In the Linux kernel, the following vulnerability has been resolved: net: ipv4: fix memory leak in netlbl_cipsov4_add_std Reported by syzkaller: BUG: memory leak unreferenced object 0xffff888105df7000 (size 64): comm "syz-executor842", pid 360, jiffies 4294824824 (age 22.546s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000e67ed558>] kmalloc include/linux/slab.h:590 [inline] [<00000000e67ed558>] kzalloc include/linux/slab.h:720 [inline] [<00000000e67ed558>] netlbl_cipsov4_add_std net/netlabel/netlabel_cipso_v4.c:145 [inline] [<00000000e67ed558>] netlbl_cipsov4_add+0x390/0x2340 net/netlabel/netlabel_cipso_v4.c:416 [<0000000006040154>] genl_family_rcv_msg_doit.isra.0+0x20e/0x320 net/netlink/genetlink.c:739 [<00000000204d7a1c>] genl_family_rcv_msg net/netlink/genetlink.c:783 [inline] [<00000000204d7a1c>] genl_rcv_msg+0x2bf/0x4f0 net/netlink/genetlink.c:800 [<00000000c0d6a995>] netlink_rcv_skb+0x134/0x3d0 net/netlink/af_netlink.c:2504 [<00000000d78b9d2c>] genl_rcv+0x24/0x40 net/netlink/genetlink.c:811 [<000000009733081b>] netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] [<000000009733081b>] netlink_unicast+0x4a0/0x6a0 net/netlink/af_netlink.c:1340 [<00000000d5fd43b8>] netlink_sendmsg+0x789/0xc70 net/netlink/af_netlink.c:1929 [<000000000a2d1e40>] sock_sendmsg_nosec net/socket.c:654 [inline] [<000000000a2d1e40>] sock_sendmsg+0x139/0x170 net/socket.c:674 [<00000000321d1969>] ____sys_sendmsg+0x658/0x7d0 net/socket.c:2350 [<00000000964e16bc>] ___sys_sendmsg+0xf8/0x170 net/socket.c:2404 [<000000001615e288>] __sys_sendmsg+0xd3/0x190 net/socket.c:2433 [<000000004ee8b6a5>] do_syscall_64+0x37/0x90 arch/x86/entry/common.c:47 [<00000000171c7cee>] entry_SYSCALL_64_after_hwframe+0x44/0xae The memory of doi_def->map.std pointing is allocated in netlbl_cipsov4_add_std, but no place has freed it. It should be freed in cipso_v4_doi_free which frees the cipso DOI resource.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-47250 is a Linux kernel memory leak in the NetLabel CIPSOv4 configuration path. Repeated triggering could waste kernel memory and contribute to denial of service. The source bundle does not report code execution, data theft, or active exploitation.

Executive priority

Treat this as a routine but real kernel maintenance item. It is not flagged as actively exploited, but kernel memory leaks can degrade service availability on exposed or multi-tenant systems.

Technical view

The flaw is in netlbl_cipsov4_add_std, where doi_def->map.std is allocated but not freed. The fix routes cleanup through cipso_v4_doi_free. The trace shows generic netlink handling, but the bundle does not state required privileges or attack prerequisites.

Likely exposure

Exposure is likely limited to Linux systems running affected kernel versions where the NetLabel CIPSOv4 add path is reachable. The bundle lists affected Linux kernel lines including older 4.x, 5.4, 5.10, 5.12, and 5.13 versions, with stable fix commits referenced.

Exploitation context

The issue was reported by syzkaller as a memory leak. KEV is false, and the provided sources do not claim public exploitation. Practical impact depends on whether an attacker can reach the relevant netlink configuration path and repeatedly trigger allocation.

Researcher notes

The source evidence supports a memory leak in Linux NetLabel CIPSOv4 cleanup. It does not provide CVSS, CWE, privilege requirements, proof of exploitability beyond syzkaller reproduction, or distribution-specific fixed versions.

Mitigation direction

  • Update to an OS vendor kernel containing the referenced stable fix.
  • Check Linux distribution advisories for the exact fixed package version.
  • Prioritize shared hosts, container hosts, and systems with untrusted local workloads.
  • Monitor kernel memory pressure until patched.
  • Avoid direct wrangler-style assumptions; follow vendor kernel guidance only.

Validation and detection

  • Inventory kernel versions across Linux hosts.
  • Map versions to vendor advisories or the referenced stable commits.
  • Check whether NetLabel or CIPSOv4 functionality is used operationally.
  • Review logs and monitoring for unexplained kernel memory growth.
  • Confirm patched kernels after reboot using standard asset data.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2021-47250 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
9Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux96cb8e3313c7a12e026c1ed510522ae6f6023875, 96cb8e3313c7a12e026c1ed510522ae6f6023875, 96cb8e3313c7a12e026c1ed510522ae6f6023875, 96cb8e3313c7a12e026c1ed510522ae6f6023875, 96cb8e3313c7a12e026c1ed510522ae6f6023875, 96cb8e3313c7a12e026c1ed510522ae6f6023875, 96cb8e3313c7a12e026c1ed510522ae6f6023875, 96cb8e3313c7a12e026c1ed510522ae6f6023875unaffected
LinuxLinux2.6.19, 0, 4.4.274, 4.9.274, 4.14.238, 4.19.196, 5.4.128, 5.10.46, 5.12.13, 5.13affected
Weakness

CWE details

No CWE listed

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